Device for shielding electrical terminals



Dec. 24, 1957 J. SCHNEIDERMAN 2,817,593 nsvxcs FOR sumwmc ELECTRICAL TERMINALS Filed Jan. 4, 1954 Jq ,0 W Ii- INVENTOR. Jasep/zflzwzdermarz United States Patent DEVICE FOR SHIELDING ELECTRICAL TERMINALS Joseph Schneiderrnan, Chicago, 11].

Application January 4, 1954, Serial No. 402,062

1 Claim. (Cl. 174-5) This invention relates to a device for shielding electrical terminals. In particular it has reference to improvements in the device disclosed in my U. S. Patent No. 2,482,129.

In that patent I have shown a device primarily intended for shielding electrical conductors subject to dangerous potentials against inadvertent contact, for example, the well-known, hooked connections whereby an interior type of suspended neon sign is carried on its transformer box.

Such signs are quite frequently located close to show windows of business establishments. Accordingly, when the window is to be Washed it is desirable to remove the sign to avoid accidental breakage thereof. To this end the terminals from the transformer and the correspond ing terminals of the tubing are generally of hook form, so that rapid engagement and disengagement of the sign letters proper may be elfected. However, these joints comprising, as they do, bare conductors connectible to a high voltage, are required by law to be protected by a sleeve of insulating material. Because it is expedient for the sign manufacturer to do so he customarily furnishes lengths of glass tubing arranged normally to surround the exposed conductors and capable of being removed or shifted out of the Way when disconnecting the sign. However, the glass sleeves are easily broken; are, through negligence, or indifference, hardly ever replaced, and an ever-present hazard is the result.

This invention provides protective means for accomplishing the purpose set forth which is foolproof in use, inexpensive, proof against fracture, and capable of being installed without change in any presently known types of signs for which the device is intended.

Another object is to provide a device as aforesaid which lends itself well to molding in polyethylene or similar flexible plastic composition in order to answer the requirement of infrangibility.

Another object resides in providing means for temporarily maintaining the movable shield portion of the device in a shifted position facilitating manipulation of the hooked junction.

Other objects will appear from the following description which, taken with the accompanying drawing, discloses a preferred form in which the invention may be embodied in practice.

In this drawing:

Fig. l is a front elevational view of a complete neon sign of a typical form to which the invention adjunct is adapted;

Fig. 2 is an enlarged detail of a portion of Fig. 1, partly in cross section, showing the device in its relation to other parts when in active position;

Fig. 3 is a view similar to that of Fig. 2 but showing the device in inactive position;

Fig. 4 is a View in perspective of a modified form of the device separated from its normal assembly;

Fig. 5 is a cross section taken on the line 5-5 of Fig. 2;

Fig. 6 is a cross section taken on the line 6-6 of Fig. 3; and

Fig. 7 is a perspective view of a further alternative mode of carrying the invention into practice.

Regarded in a broad sense, the invention comprehends the provision of a fixed part arranged for clamping to one of the conductors, e. g., that one depending from the customary transformer box, and a movable part slidably carried on the fixed part and capable of being positioned normally to shield the bare hook connections and which can be lifted to expose the same for removal and re-attachment of the sign. Means are provided for maintaining the movable part positively in active and inactive positions. The device is so constructed that, when once attached to the conductor, no tools are required for subsequent manipulation thereof.

While the invention will be illustrated by reference to an environment wherein the conductors are vertically aligned it will become apparent that such operative position is not essential as cases may arise where the invention is equally adaptable to conductors which are otherwise oriented.

Turning to the drawing I have shown a neon sign unit of a common type comprising a box 10 enclosing a transformer and permanently supported in any convenient manner. The leads 1111 from the secondary of the transformer exit from the box 10 through grommets 12-12, and which leads are insulated over their exposed extent except for a bare hook portion 1515 respectively adapted to receive corresponding hook portions 1616 fused into the ends of the glass tubing 17 out of which the lettering of the sign proper is formed. As will be understood, the tubing 17 is capable of being rapidly disconnected when it or an area near it is to be worked on, e. g., washing of the plate glass of a display window near which the sign may be suspended.

The invention comprises two principal parts, a fixed core or body 21 and a movable shield or sleeve 22. Preferably these parts are made of polyethylene or other plastic or non-plastic composition having the desired primary attributes of high impact strength, ease of molding or machining, resiliency and low cost. Obviously, the material employed must be characterized by sufficient rigidity to enable initial installation and function together with that degree 'of resiliency which will make fracture virtually impossible. Polyethylene has been found suitable for all these requirements.

Body 21 includes a hollow, cylindrical, part 31 having a bore 32 just slightly larger than the diameter of the conductor 11 over which it may be slipped and clamped by means of a split ring 33 and bolt 34. Preferably, the part 31 is split at 36 to allow easy compression thereof. Obviously, the clamping means may be made integral with the part 31. At its lower end the sleeve 21 is provided with a flange 38 or equivalent enlargement for a purpose to appear.

The sleeve 22 is generally of inverted cup shape including a cylindrical side wall 41 and an end wall 42 having a central, circular aperture 43 providing a sliding and rotatable fit over the part 31. A pair of keyways or notches 4646 are formed in the periphery of the aperture 43 and corresponding splines or projections 47 are provided on the exterior of the part 31 whereby when the notches 46 and projections 47 are aligned the sleeve 22 may be lifted from shielding position to expose the terminals for manipulation of the sign.

The flange 38 and the lower pair of projections 47-47 are positioned with respect to the thickness of the end wall 42 of the sleeve in order that when the latter has been rotated to a position whereat the notches 4646 and pair of lower projections 47-47 are out of alignment some degree of friction is present. Thus, the sleeve is retained in its operative position by positive means whereby accidental alignment of the notches 46-46 and projections 47- 37 is obviated. In this manner the sleeve is incapable of being vibrated or inadvertently moved to an upper position to expose the terminals and to present a hazard thereby.

When the sleeve has been moved to inactive position (Fig. 3) the wall 42 may rest on the upper pair of projections 47-47 to retain the sleeve out of the way pending disconnection and re-connection of the sign.

In Fig. 4 there is shown an alternative embodiment differentiated from that previously described by the employment of continuous projections 47a47a in substitution of the two pairs heretofore detailed. Under some circumstances, e. g., expediency of molding, this latter alternative may oe preferred. Additionally, in the case of both forms of the inventions disclosed a single projection 47 at the top and at the bottom or a single spline 47a may be utilized together with a single notch 46. However, by employing the duplicate arrangement it is only necessary that the sleeve be rotated over an angle of less than lSO" to effect register of the notches and projections whereas the singular arrangement requires exploration over substantially 360 to effect the same function.

The form of invention illustrated in Fig. 7 lends itself well to fabrication from polyethylene. In this construction the sleeve 22a includes the aperture 43a from the periphery of which extends inwardly a projection or lug 61. The body Ilia includes the cylindrical portion 31a having a recess or slot 62 which comprises an axially extending section as and circumferentially extending sections 64 and 65. in view of the description given in connection with the other embodiments it will be apparent that the sleeve 22:: may be positively and. frictionally retained in active and inactive positions by rotation of the lug 61 into the sections 65 or :54, respectively, and out of register with the section 63, whereas upon effecting such register the sleeve is freed for axial shifting movement.

Initial engagement of the lug 61 within the recess or slot 62 is easily effected by bodily forcing the parts into such assembly. By virtue of the elasticity of the material both the body 21:: and lug 61 will yield to some extent so that the necessary interengagement may be effected comparatively easily. After the body 21a is secured to the conductor it is supported from within and is therefore incapable of that degree of collapse which will allow the lug 61 to be accidentally released. Moreover, the lug 61, being relatively short, is not readily deformed to effect release under similar circumstances.

Obviously the sections 64 and 65 need not extend circumferentially on both sides of the section 63. However, the arrangement shown and described has the advantage that the operator need pay no heed to direction of rotation as locking will occur in either sense. Also it is within contemplation for one of the sections 64 or 65 to extend in one direction and one of them in the opposite direction, in which case locking and unlocking movements may occur in the same rotational sense sequentially, and therefore in a more logical manner.

While I have shown particular embodiments of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claim to cover any such modifications as fall within the true spirit and scope of my invention.

I claim:

A device for shielding a pair of disconnectible electrical terminals forming the exposed ends of a pair of axially aligned, insulated conductors comprising a fixed part including means for securernent to one of the conductors and having an axial passage for passage of the conductor and said fixed part including a cylindrical portion; and a sleeve of greater internal diameter than said cylindrical portion having a lateral imperforate wall and shiftable axially with respect to said cylindrical portion, said sleeve having an inwardly directed flange adjacent one end thereof, said flange defining an internal aperture providing a sliding fit with and engaged over said cylindrical portion, said sleeve normally being positioned to shield said terminals and slidably actuatable upon said cylindrical portion to expose the same, male means on said cylindrical portion and complementary female means defined by portions of said flange, said male and female means being relatively so dimensioned and positioned that upon relative rotation of said sleeve and fixed part said male and female means are brought into register for movement of the male through the female means for shifting movement of said sleeve to terminal-exposing position and, upon further relative rotation of said sleeve and fixed part, said male and female means may be moved out of register tem' porarily to maintain said sleeve in terminal-exposing position and, upon reverse axial shifting thereof, to retain said sleeve in terminal-shielding position, said cylindrical section terminating within said sleeve in an enlargement greater than said aperture to limit the axial position of said sleeve as the same is shifted to terminal-shielding position.

References Cited in the file of this patent UNITED STATES PATENTS 972,989 Bond Oct. 18, 1910 1,932,436 Barnhill Oct. 31, 1933 2,315,516 Gray Apr. 6, 1943 2,355,922 Minero Aug. 15, 1944 2,441,689 Daniel May 18, 1948 2,482,129 Schneiderman Sept. 20, 1949 

